Type of test Urine
Normal findings
MA: < 2 mg/dL
MA/creatinine ratio:
Males: < 17 mg/g creatinine
Females: < 25 mg/g creatinine
Test explanation and related physiology
Microalbuminuria refers to an albumin concentration in the urine that is greater than normal but not detectable with routine protein testing. Normally, only small amounts of albumin are filtered through the renal glomeruli, and that small quantity can be reabsorbed by the renal tubules. However, when the increased glomerular permeability of albumin overcomes tubular reabsorption capability, albumin is spilled in the urine. Preceding this stage of disease is a period of microalbuminuria that would normally go undetected. Therefore MA is an early indication of renal disease.
For a patient with diabetes, the amount of albumin in the urine is related to duration of the disease and the degree of glycemic control. MA is the earliest indicator for the development of diabetic complications (nephropathy, cardiovascular disease [CVD], and hypertension). MA can identify diabetic nephropathy 5 years before routine protein urine tests. Patients with diabetes with elevated MA have a 5- to 10-fold increase in the occurrence of CVD mortality, retinopathy, and end-stage kidney disease.
All patients with diabetes older than the age of 12 and less than 70 years should be screened annually for MA. This can be done through a spot urine specimen by using a semiquantitative Micral Urine Test Strip. If MA is present, the test should be repeated two more times. If two of three MA urine test results are positive, a quantitative measurement should be performed. The preferred specimen is a 24-hour collection, but a 10-hour overnight collection (9 p.m.-7 a.m.) or a random collection are acceptable. Correcting albumin for creatinine excretion rates has value with respect to diabetic renal involvement, and it is now suggested that an albumin/creatinine ratio from a random urine specimen is a valid screening tool. Twenty-four-hour excretion over 30 mg/24 hours or an excretion rate over 20 mcg/min is considered abnormal.
The presence of MA in people without diabetes is an early indicator of lower life expectancy from CVD and hypertension. Nondiabetic nephropathies also may be associated with micro albuminuria. Life insurance underwriters are increasingly using MA testing to indicate life expectancy.
Interfering factors
• Urinary tract infection, blood, or acid–base abnormalities can cause elevated MA levels.
* Oxytetracycline may interfere with test results.
Procedure and patient care
• See inside front cover for Routine Urine Testing.
• Ensure that the patient does not have any acute infection or urinary bleeding that could cause a false-positive result.
• If the urine specimen contains vaginal discharge or bleeding, a clean-catch or midstream specimen will be needed.
• Ensure that the urine sample is at room temperature.
• If using a Micral Urine Test Strip:
1. Dip the test strip into the urine for 5 seconds.
2. Allow the strip to dry for 1 minute.
3. Compare the strip with the color scale on the label.
• If a 24-hour urine collection is requested, the specimen should be refrigerated.
* If the results are positive, inform the patient that the test should be repeated in 1 week.
Abnormal findings
Increased levels
- Diabetes mellitus
- Hypertension
- Cardiovascular disease
- Nephropathy
- Urinary bleeding
- Hemoglobinuria
- Myoglobinuria
